Question

A three-phase asynchronous motor with squirrel cage rotor is available with:
Voltage: 230/400 V
Frequency: 50 Hz
Number of Poles: 10
In addition, the following parameters of the equivalent circuit are known:
R1 = 0.5  X1 = 3  R´2 = 0.8  X´2 = 3.5 
Mechanical losses are considered to be negligible and the parallel branch of the
equivalent circuit.
1. Draw the approximate equivalent circuit of the motor without the branch in parallel.
2. Indicates the connection mode of the motor stator when connected to a three-phase voltage network
Composed 400 V (i.e. 400 V line). Justify the answer.
3. What current will this motor draw at startup?
4. Considering that the slip at full load is 4%, calculate:
4.1. The absorbed current.
4.2. The developed mechanical power.
4.3. The useful torque.
4.4. The active power absorbed from the network.
4.5. Performance.
5. At what speed is the maximum torque obtained?
6. How much is the maximum torque worth?

Answer 1